Black Belt Sudoku(r)

The book has 300 puzzles, but this one had FOUR puzzles that I was able to do. Buying from this seller is a disgrace to all sellers. The book was well used, scribbled in by kids, dirty as can be and I threw it away. I will NEVER buy from this seller again and I advise all readers to do the same.

I've worked all four books, white, green, brown and black, and I'm not sure why these were supposed to be difficult. I actually found some of the ones in the green belt bookSecond-Degree Green Belt Sudoku (Martial Arts Sudoku) were much more difficult than these. In any case, they're still fun and easily worked with whatever technique you generally employ to solve them. I did find that mixing my techniques tended to lead me more often astray, and that I didn't generally discover my error until I had nearly finished the thing. My method has become one of see if the cross-overs find a lot of results then finish it that way. If you don't get a lot of results on your first pass through the columns and rows, then start over and do it the old fashioned list-the-numbers way!

The common complaint of this book seems to be that the puzzles are easy. Well, that's true. Sudoku puzzles can all be solved in polynomial time, which in layman's terms means that a computer can quickly solve one by blindly following an algorithm. They as a genre are not challenging. Doing these are fun when you have time to kill, for example I would do some while waiting for a flight. If you're looking for "hard" problems, quit whining about the polynomial time complex nature of Sudoku and try your hand at something actually HARD, like cryptography.

I look forward to doing one of these puzzles every morning to kick-start my brain! Good size for carrying around.

I've really enjoyed this one. Some are real wooly boogers and others are just challenging. I'm addicted to these things!